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Occurrence Patterns and Control Methods of Cherry Brown Spot Shot Hole Disease

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Symptoms: Small brown, grayish-brown, or purplish-brown spots initially appear on the leaves, gradually forming circular lesions that are non-water-soaked and opaque, with no yellow-green halo around the lesions, 2-4 in diameter, with clear boundaries and a purplish-brown outer margin. In the later stage, the center turns white or brown, slightly zonate, and the lesions die and fall off, forming irregular shot holes. 2. Occurrence patterns: The pathogen overwinters on fallen leaves and spreads by wind and rain in the following spring. The disease begins in June, with the peak period from August to September. Heavy rainfall promotes disease occurrence and epidemic, and weakened tree vigor leads to severe disease. 3. Control methods:

Symptoms: Small brown, grayish-brown, or purplish-brown spots initially appear on the leaves, gradually forming circular lesions that are non-water-soaked and opaque, with no yellow-green halo around the lesions, 2-4 in diameter, with clear boundaries and a purplish-brown outer margin. In the later stage, the center turns white or brown, slightly zonate, and the lesions die and fall off, forming irregular shot holes.

2. Occurrence patterns: The pathogen overwinters on fallen leaves and spreads by wind and rain in the following spring. The disease begins in June, with the peak period from August to September. Heavy rainfall promotes disease occurrence and epidemic, and weakened tree vigor leads to severe disease.

3. Control methods: (1) In conjunction with winter pruning, cut off diseased branches and clear away dead branches and fallen leaves to reduce infection sources.

(2) Spray lime sulfur mixture before bud break in spring for protection.

(3) In the early stage of disease onset in June, spray fungicides such as ridomil mancozeb, kasugamycin, and thiophanate-methyl for control.

Bacterial Shot Hole Disease

1. Symptoms: The disease mainly occurs on leaves, and twigs can also be infected. Small water-soaked brown spots first appear on the leaves, then expand into circular or angular lesions, brown or purplish-brown, with a yellow-green halo around the lesions. Under humid conditions, pale yellow bacterial ooze appears on the underside of the lesions, and in the later stage the lesions fall off forming shot holes. Infected twigs form black sunken and cracked areas.

2. Occurrence patterns: The pathogen overwinters in lesions on twigs and in diseased buds, and spreads by wind, rain, and insects in spring. Continuous overcast and rainy weather or severe damage by aphids and leafhoppers can easily cause disease epidemics.

3. Control methods:

(1) Prune rationally to increase ventilation and light penetration; fertilize rationally to enhance growth vigor.

(2) Spray Bordeaux mixture before bud break in spring to eliminate the pathogen.

(3) In the early stage of disease onset, spray fungicides such as carbendazim and copper hydroxide for control.

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